Java并发库-AtomicReferenceABA

package org.walkerljl.practice.concurrent;
    
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicReference;
    
/**
 * AtomicReferenceABATest
 *
 * @author lijunlin
 */
public class AtomicReferenceABATest {
    
    private static final AtomicReference<String> ATOMIC_REFERENCE = new AtomicReference<String>("abc");
    private static final Random RANDOM_OBJECT = new Random();
    
    public static void main(String[] args) throws InterruptedException {
        final CountDownLatch startCountDownLatch = new CountDownLatch(1);
        Thread[] threads = new Thread[20];
        for (int i = 0; i < 20; i++) {
            final int num = i;
            threads[i] = new Thread() {
                @Override
                public void run() {
                    String oldValue = ATOMIC_REFERENCE.get();
                    try {
                        startCountDownLatch.await();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    try {
                        Thread.sleep(RANDOM_OBJECT.nextInt() & 500);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    if (ATOMIC_REFERENCE.compareAndSet(oldValue, oldValue + num)) {
                        System.out.println("线程:" + num + "，进行了对象修改");
                    }
                }
            };
            threads[i].start();
        }
        Thread.sleep(200);
        startCountDownLatch.countDown();
        new Thread() {
            @Override
            public void run() {
                try {
                    Thread.sleep(RANDOM_OBJECT.nextInt() & 200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
    
                while (!ATOMIC_REFERENCE.compareAndSet(ATOMIC_REFERENCE.get(), "abc")) {
                }
                ;
    
                System.out.println("已经修改为原始值");
            }
        }.start();
    }
}